A first step in sample analysis typically involves collecting the sample. For example, a first step in a biological analysis such as RNA gene expression profiling or protein biomarker profiling is to collect a particular sample so that its biochemical constituents can be analyzed. However, prior to such analysis, a solid sample specimen, typically, is prepared by deconstructing it into a plurality of smaller fragments of the specimen to enable more accurate analysis.
A challenge of sample preparation is that the types of samples are diverse. For example, samples may be biological, non-biological or a combination thereof. They may be from animals or plants. Samples may include, without limitation, cells, tissues, organelles, bones, seeds, chemical compounds, minerals, metals, or any other material for which analysis is desired.
Sample preparation is particularly challenging for solid biological samples, such as tissue samples. Physical and/or chemical approaches are often employed to disrupt and homogenize the solid sample for biochemical extraction. While appearing deceptively simple, transitioning a sample of biologically active tissue, for example, on the order of 1 gram, to a plurality of biomolecules that are stabilized and isolated in an appropriate analytical solution is exceedingly complex, very difficult to control, and prone to introduction of errors and/or sample constituent degradation.
Another challenge associated with sample preparation relates to the lability of the target molecules. For some applications, an overriding criterion is to retain the native biochemical environment prior to sample collection and throughout the extraction process, without perturbing the biochemical constituents to be analyzed. For example, RNases are extremely robust and may significantly degrade the mRNA profile of a tissue sample if the RNases are not immediately stabilized (typically thermal or chemical inactivation) at the time of tissue collection and during sample processing or homogenization. Often, to minimize perturbation of the biochemical profile of the sample, the tissue is flash-frozen (e.g., via direct immersion of the sample following procurement in liquid nitrogen) and stored at cryogenic temperatures (e.g., −80 degrees C. or lower), which inhibits degradative processes.